National Instruments SCXI-1163 - Manual (Page 55)

© National Instruments Corporation 5-1 SCXI-1163 User Manual
Chapter 5
Programming
This chapter contains a functional programming description of the SCXI-1163 and Slot 0.
Note: If you plan to use a programming software package such as NI-DAQ, LabWindows, or
LabVIEW with your SCXI-1163 board, you do not need to read this chapter.
Programming Considerations
Programming the SCXI-1163 involves writing to the Data Register. Programming the data
acquisition boards involves writes to their registers. See your data acquisition board user manual
for more information. The programming instructions list the sequence of steps to take. The
instructions are language independent; that is, they instruct you to write a value to a given
register without presenting the actual code.
Notation
For the bit patterns to be written, the following symbols are used:
0 binary zero
1 binary one
X don't care; either zero or one may be written
The bit patterns are presented MSB first, left to right.
Register Writes
This section describes how to write to the Data Register including the procedure for writing to
the Slot-Select Register to select the appropriate slot. For timing specifics, refer to the
Timing
Requirements and Communication Protocol section in Chapter 2, Configuration and Installation .
Table 5-1 lists the rear signal connector pin equivalences to the different National Instruments
data acquisition boards. See also Appendix E,
SCXI-1163 Cabling . The Data Register is a write-
only register.
The different bits in this register control independent output channels. There are times when you
may want to set a specific channel or channels without affecting the remaining channels.
However, a write to the Data Register affects all channels simultaneously. You cannot read the
register to determine which channels have been set or reset in the past; therefore, you should
maintain a software copy of the channel states. You can then read the software copy to
determine the status of the channels. To change the state of a single channel without disturbing
the remaining channels, change the bit that controls the channel of interest, set all other bits to
the states last written to them, and rewrite to the Data Register.